Coincidence detection is used either to detect individual coincidence events as they occur or to count them for the purpose of providing summary data after some interval of time. Coincidence circuits are widely used in particle physics experiments and in other areas of science and technology. Coincidence circuits were the subject of the Nobel Prize for Physics in 1954, and are also disclosed in U.S. Pat. No. 7,057,172, to Goldie, which is incorporated in its entirety herein by reference.
Classically, coincidence detection is realized using either analog or digital electronic techniques. In the analog realization, the time between an event in one channel and an event in a second channel is recorded and those times within a certain range are designated “coincidence events.” In a digital realization, use is made of the “and” function, which is well known in digital electronics. A coincidence occurs when a signal pulse on one input AND a second signal pulse on another input happen together. This requires setting time delays to assure that signal from coincident event arrive at the AND function circuit at the same time making a practical coincidence detection somewhat more complex.
Multi-coincidences (coincidences between more than two events) are of interest in scientific and diagnostic equipment troubleshooting, intelligence gathering, environmental forecasting and other contexts. Real-world designs must implement a specified time window in which coincidences would be counted, and must allow for arbitrary but fixed delays between channels.
Real world systems must also take into account other problems that may arise from the varying size and shape of the signal pulses. When coincidence detection between more than two channels is required, the complexity of these two channel-based solutions increases greatly, often making their application unfeasible.
It is thus desirable to have a simplified, reliable coincidence detection system which can be used to detect multi-coincidences and which provides for equivalent (symmetrical) treatment of channel inputs having varying size and shape of the signal pulses.
It is further desirable to have a system which eliminates common problems for asynchronous time-to-amplitude converters and which has external clock synchronization capability.
It is further desirable to have a system capable of high data-transfer rates that ensure that detection rates are not limited by data-transfer rates (e.g, detection rates up to two hundred million events per second).
It is further desirable to have a simplified system design which may be adapted for use with computer peripherals (e.g., keyboards, mice, memory sticks, etc.).